Erasable sign

ABSTRACT

A sign comprises a base layer and a transparent or translucent upper sheet over the base layer. An icon or indicia of the sign is associated with the base layer or is printed on the upper sheet. The upper sheet and base layer are releasably adhered together under pressure applied on the upper sheet which causes the icon or indicia to be displayed. When the upper sheet is released from the base layer the icon or indicia is erased. In another embodiment the icon or indicia is displayed when the upper sheet is released from the base layer, and is erased when the upper sheet is pressed to adhere to the base layer.

FIELD OF INVENTION

The invention comprises an erasable sign. The sign of the invention maybe a separate sign or may be an integral part of another product such asa label or book for example.

SUMMARY OF INVENTION

The present invention provides a form of sign which may normally beblank or erased, but can be operated to display a predetermined icon orindicia including one or more words, which can then be erased again atwill and so on. The icon or indicia may be any graphical symbol of anytype, or any word or words, or any combination of one or more symbol(s)or one or more word(s).

In broad terms in one aspect the invention comprises an erasable signcomprising a base layer comprising a contrasting icon or indicia in orbelow the base layer and an upper sheet extending over the base layer,the upper sheet and the base layer being releasably adhesive togetherunder pressure applied on the upper sheet, and the base layer icon orindicia being visible through the upper sheet when the upper sheet iscaused to releasably adhere to the base layer and being substantiallyless visible and preferably generally invisible when the upper sheet isreleased from the base layer.

The base layer may be formed in the shape of the icon or indicia as apositive image of the icon or indicia, or as a negative image, or theicon or indicia may be printed on a surface beneath the base layer as apositive or negative image and the base layer applied over said surfaceas a clear or substantially clear coating.

In broad terms in another aspect the invention comprises an erasablesign comprising a base layer and an upper sheet extending over the baselayer with an icon or indicia printed on the upper sheet, the uppersheet and the base layer being releasably adhesive together underpressure applied on the upper sheet, and the icon or indicia beingvisible when the upper sheet is released from the base layer and beingsubstantially less visible or generally invisible when pressure isapplied on the upper sheet to cause the upper sheet to adhere to thebase layer.

The icon or indicia may be printed on the underside or top of the uppersheet, as a positive or negative image.

In broad terms in a further aspect the invention comprises an erasablesign comprising a base layer and an upper sheet extending over the baselayer with an icon or indicia printed on the upper sheet as a negativeimage, the upper sheet and the base layer being releasably adhesivetogether under pressure applied on the upper sheet, and the icon orindicia being visible when pressure is applied on the upper sheet tocause the upper sheet to adhere to the base layer and beingsubstantially less visible and preferably generally invisible when theupper sheet is released from the base layer. Preferably the icon orindicia image is printed on the upper sheet with a colour which is onlya medium contrast with the colour of the base layer, such as a lightergrey if the base layer is a dark grey or a lighter red if the base layeris a darker red, to assist in making the icon less visible or generallyinvisible when erased.

Preferably in all signs of the invention the upper sheet and base layerare sufficiently releasably adhesive together that both the upper sheetcan be caused to adhere to the base layer by pressure applied manuallyon the upper sheet and also that the upper sheet can be released fromthe base layer by wiping a users finger or thumb across the top surfaceof the upper sheet to cause the upper sheet to move relative to the baselayer. Preferably in such signs of the invention the upper sheet alsoextends over a "wipe-start" region adjacent the base layer in whichwipe-start region the upper sheet and the base layer are not adhesivetogether, over which region a users finger or thumb may be placed tobegin the finger wipe action to separate the upper sheet from the baselayer.

The sign may have a contact adhesive applied to the rear surface or apart of the rear surface of the sign enabling it to be stuck onto anyother object or item. Also the sign may form part of an adhesive labelalso having a label area as well as incorporating a sign of theinvention. Alternatively the sign may comprise part of or be a noveltyor other card or item having no adhesive rear surface. Alternativelyagain, instead of having a backing sheet providing a rear surfacecarrying the base layer, the base layer of the sign and upper sheetabove it could be applied directly and permanently to an item duringmanufacture such as the cover of a folder, a phone card, a ruler or anyother solid object.

DESCRIPTION OF DRAWINGS

Preferred forms of signs of the invention will now be described by wayof example and without intending to be limiting as to detail, withreference to the accompanying drawings, wherein:

FIG. 1 shows one preferred form of sign of the invention with the uppersheet released from the base layer so that a base layer icon or indiciaof the sign is not visible,

FIG. 2 shows the sign of FIG. 1 with the upper sheet adhered to the baselayer so that the icon or indicia is visible and showing the start offinger wipe action to release the upper sheet from the base layer toagain erase the icon or indicia,

FIG. 3 shows the sign of FIGS. 1 and 2 in cross-section along line 3--3of FIG. 2,

FIG. 4 shows the sign of FIGS. 1 and 2 in cross-section along line 4--4of FIG. 2,

FIG. 5 shows another preferred form of sign of the invention similar tothat of FIGS. 1 to 4, in cross-section,

FIG. 6 shows a preferred form of sign of the invention with the uppersheet adhered to the base layer so that an upper sheet icon or indiciais not visible and showing the start of finger wipe action to releasethe upper sheet from the base layer to make the icon or indicia visible,

FIG. 7 shows the sign of FIG. 6 with the icon or indicia visible,

FIG. 8 shows the sign of FIGS. 6 and 7 in cross-section along line 8--8of FIG. 7,

FIG. 9 shows the sign of FIGS. 6 and 7 in cross-section along line 9--9of FIG. 7,

FIG. 10 shows another form of sign of the invention with the upper sheetreleased from the base layer so that an upper sheet icon or indicia isnot visible,

FIG. 11 shows the erasable sign of FIG. 10 with the upper sheet adheredto the base layer so that an upper sheet icon or indicia is visible andshowing the start of finger wipe action to release the upper sheet fromthe base layer to make the icon or indicia not visible,

FIG. 12 shows the sign FIGS. 10 and 11 in cross-section along line12--12 of FIG. 11,

FIG. 13 shows the sign of FIGS. 10 and 11 in cross-section along line13--13 of FIG. 11,

FIG. 14 shows another preferred form of sign of the invention in onestate i.e. with the upper sheet released from the base layer so that anupper sheet icon (an apple shape in negative image) is visible and anindicia of the base layer is not visible,

FIG. 15 shows the sign of FIG. 14 with the upper sheet adhered to thebase layer so that the base layer icon or indicia (the word "apple") isvisible within the negative image upper sheet icon,

FIG. 16 shows a sign similar to that of FIGS. 14 and 15 but slightlydifferent, with the upper sheet pressed against the base layer so thatthe base layer icon or indicia is visible but (in this version) theupper sheet icon or indicia is less visible,

FIG.17 is an exploded view of the sign of FIGS. 14 and

FIG. 18 shows the sign of FIGS. 14 to 17 in cross-section,

FIG. 19 shows a further sign of the invention having a small slidingcursor operating between the upper sheet and base layer of the sign forerasure, and

FIG. 20 shows the sign of FIG. 19 along line 20--20 of FIG. 19.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings, the sign of the invention in all casescomprises a base layer 2 and an upper sheet 3 extending over the baselayer.

The base layer 2 comprises a layer of wax or similar synthetic materialwhich will adhere with the upper sheet 3 when they are pressed togetherbut which allows the upper sheet 3 to be subsequently released from thebase layer 2 as will be described. The base layer 2 may be coated onto abacking sheet

Suitable materials for forming the base layer include waxes such asparaffin wax, blends of paraffin wax with other waxes, blends of otherwaxes, and other substances such as synthetic wax like substances havinga waxy consistency, which can be applied as a thin layer and will adherewith the upper layer. Some base layers such as some synthetic wax-likebase layers may be coloured by having a dye added, or alternatively thebase layer may be made to appear coloured by printing a colour on asubstrate and then applying a clear or near clear wax or similarmaterial over the coloured surface to form a coloured base layer.

The base layer may comprise any other suitable material than wax, whichhowever will adhere with the upper sheet 3 under localised pressure butwhich also allows the upper sheet to be subsequently released from thebase layer.

The backing sheet 1 may consist of a layer of light card or paper orplastic or other rigid or non-rigid substrate. The backing sheet 1 mayhave a coating of contact adhesive on its rear surface or a part of itsrear surface by which the sign may be stuck to an object. Alternativelythe backing sheet may be the page of a book where the sign is carried bythe page of a child's book as a novelty for example, or a novelty cardof a series that children may collect, for example.

It is possible that the material of the backing sheet 1 could form thebase layer so that the base layer 2 and backing sheet 1 are one and thesame. The base layer 2 can also be directly applied to the surface of anobject which is to have an erasable sign permanently fixed to orintegral with it, such as a rigid file cover or part thereof, a keyring, an in/out notice board or the like.

The upper sheet 3 is preferably translucent and may comprise atranslucent plastic film, tracing paper or the like. A clear plasticfilm may be given qualities of translucence by etching, texturing orcalendaring the film and particularly the bottom surface of the film,for example. This may also assist the upper sheet to adhere with thebase layer in use. A clear film may also be made translucent by printingthe film with a translucent ink or a layer of a conventional opaque inkwhich is thin enough to make the film appear translucent. The uppersheet 3 may be printed to define a window in the upper sheet for examplethrough which the icon or indicia of the sign is visible. Regions of theupper sheet other than such a window may be provided for carryingpermanently printed media such as advertising media.

Most preferred for forming the upper sheet are polyester films orsimilar materials preferably having a glossy or substantially glossysurface. Preferably the upper sheet is up to 100 microns and mostpreferably in the range 35 to 65 microns in thicknesses.

A protective top sheet (not shown) may be provided over the upper sheet,comprising clear plastic film for example.

In signs of the invention adjacent the base layer 2 may optionally beprovided a wipe-start region 2a. In FIGS. 1 & 2, 6 & 7, 10 & 11 and 14to 16 this wipe-start region 2a is indicated by a broken outline. Thewipe-start region 2a may be formed as shown in FIGS. 4, 5, 9, 13 and 18by applying no material of the base layer i.e. no waxy or similarmaterial, to the backing sheet 1 beneath the upper sheet 3 in thewipe-start region 2a. The region 2a may be the same width across thesign as the base layer 2 but could be of less or greater width, and ispreferably at least one finger width wide in the direction of erasurealong the length of the sign, but could be wider, or longer, for largersigns for example.

Alternatively to provide a wipe-start region the material of the baselayer 2 may extend beneath the upper sheet 3 in the wipe-start region2a, and to make the upper sheet 3 and base layer 2 non-adhesive togetherin the wipe-start region, a coating may be applied to the under surfaceof the upper sheet 3 in the wipe-start region 2a. The coating is amaterial such as a silicon or any other suitable coating, which willmake the upper sheet non-adhesive to the material of the base layer 2.In a variation a coating may be applied to the top surface of the baselayer 2 in the wipe-start region 2a, instead of applying the coating tothe undersurface of the upper sheet 3 also to make the upper sheet 3 andbase layer 2 non-adhesive together in the wipe-start region 2a.

The upper sheet 3 extends over both the base layer 2, and any wipe-startregion 2a if provided, and is fixed to the backing sheet 1 about theperiphery of the upper sheet, that is along both sides and at either endof the upper sheet, by gluing, plastic welding or other suitable meansduring manufacture. Small air vents may be provided in the form of oneor more slits or pinholes near the periphery of the product such as ator near either end for example, which can assist easy finger wipe actionof the product. Alternative to fixing the upper sheet about the entireperiphery upper sheet, the upper sheet may be fixed along at least twoopposite sides of the upper sheet or at least most of two opposite sides(in the case of a square or rectangular erasable product) but it ispreferred to fix the upper sheet about most or all of the periphery ofthe upper sheet.

Other forms of sign of the invention may comprise a wipe-start region ontwo sides of or around all or nearly all of the periphery of theerasable sign. The signs need not be square or rectangular in shape butcould be circular in overall shape for example.

In the sign of FIGS. 1 to 4 the base layer 2 is formed in the shape ofan icon or indicia such as the tick shown in the drawings. The icon orindicia instead of being the tick shown could be any other letter, word,number, symbol or the like. The icon or indicia may be made to have acontrasting colour, for example, by incorporating a dye in the wax ofthe base layer.

In use the upper sheet 3 is pressed down by pressing and repeatedlyrunning a fingernail or stylus over the upper sheet 3 for example, toblock or scribble in the required area. This will cause the upper sheet3 to adhere to the base layer icon or indicia 2 so that the icon orindicia is then clearly visible through the translucent upper sheet 3,as shown in FIG. 2.

To erase the icon or indicia so that it is substantially less visible orgenerally invisible, a user's finger or thumb is wiped across the topsurface of the upper sheet 3 from a wipe-start region 2a if provided asshown in FIG. 2. Even though the top surface of the sign may besubstantially smooth this will separate the upper sheet 3 from the baselayer 2 as the users finger moves, making the icon or indiciasubstantially invisible as shown in FIG. 1. In FIG. 1 the tick is shownin phantom outline for illustrative purposes only.

Instead of the base layer 2 being formed in the shape of the desiredicon or indicia as shown in FIGS. 1 to 4, the icon or indicia may be inkprinted beneath the base layer and the base layer may then comprise acoating of clear or near clear wax or similar over the whole of thebacking sheet (except any wipe-start region 2a). When the upper sheet ispressed against the base layer by repeatedly running a finger nail orstylus over the upper sheet 3 for example, the upper sheet will adhereto the base layer and the ink printed icon or indicia behind the baselayer will become visible through the upper sheet. The sign is erased asbefore.

As well as being translucent the upper sheet may be tinted with adifferent colour relative to the colour of the base layer icon orindicia, so that when separated from the base layer the upper sheetappears to have the colour of the upper sheet and when adhered to thebase layer the icon or indicia appears either in the colour of the baselayer or in a colour resulting from the combination of the base layerand upper sheet colour. For example, the base layer may be coloured blueand the upper sheet toned yellow; when pressed or adhered together theicon or indicia will appear green in contrast to the balance of theyellow upper sheet. The colours may be luminescent or fluorescent. Theupper sheet may also be made luminescent or fluorescent or may belightly embossed with a pattern or logo for example which may be presentas a hologram printed onto the upper sheet.

Also, to assist in making the icon or indicia less visible when theupper sheet 3 is not adhered to the base layer 2 colour of the icon orindicia may be made only medium contrast rather than high contrast, andalso the top side or under side of the upper sheet 3 may have printedonto it a pattern of small dots or wavy lines or similar which will tendto hide any shadowy image of the icon or indicia that may still bevisible through the upper sheet. Such a pattern of dots or wavy lines orsimilar should not be sufficiently dense or large to obscure the iconwhen the upper sheet is pressed to adhere to the base layer 2 to makethe icon visible. Such a pattern of dots or wavy lines or similar may beprinted with a translucent ink, or even with an opaque ink where thepattern is not too dense.

FIG. 5 shows a preferred form of sign similar to that of FIGS. 1 to 4 inthat an icon or indicia is visible when the upper sheet 3 is presseddown for example by pressing and repeatedly running a fingernail orstylus over the upper sheet 3 to block or scribble in the required area,and is erased so as to be substantially less visible or generallyinvisible when a users finger or thumb is wiped across the top surfaceof the upper sheet 3 from the wipe-start area 2a. However, in the signof FIG. 5 the coloured base layer 2 is continuous (other than in thewipe-start region 2a) and a coating 2b is applied over the top of thebase layer 2 except in a region defining the shape of the icon 2 i.e.the coating is applied as a negative image of the icon on top of thebase layer 2 (but the coating 2b could also be applied as a positiveimage). When the upper sheet 3 is pressed down by running an object overthe upper sheet 3 the upper sheet 3 will adhere to the base layer wherethe coating 2b is not applied but will not adhere to the coating 2b sothat the icon or indicia will be visible through the upper sheet. Toerase the icon or indicia so that it is no longer visible or at leastsubstantially less visible a user's finger or thumb is wiped across thetop surface of the upper sheet 3 from the region 2a as before.

FIGS. 6 to 9 show another preferred form of sign of the invention. Inthis form an icon or indicia is printed on the upper sheet 3, which isshown in the drawings as a tick printed on the underside of the uppersheet 3 as a positive image--see FIGS. 8 and 9 at 6. Alternatively thearea around the icon on indicia such as the tick may be printed so thatthe icon or indicia appears as a negative image, i.e. the icon orindicia itself remains as the translucent material with the icon orindicia possibly being given a tint of for example yellow or orange byprinting (without loss of the translucent quality). The icon or indiciamay be printed on the top side or underside of the upper sheet 3.

To cause the icon or indicia such as the tick to become substantiallyless visible or generally invisible, the upper sheet 3 is pressedagainst the backing sheet, for example by pressing and repeatedlyrunning a fingernail or suitable stylus over the upper sheet to block orscribble in the required area. This will cause the upper sheet 3 toadhere to the base layer 2 and the icon or indicia will then merge intothe colour of the base layer where the icon or indicia has been printedas a positive image, or the colour of the base layer will become visiblethrough the icon or indicia when printed as a negative (translucent)image so that the entire area about the icon or indicia will be blockedout, in a dark colour if the base layer is also a dark colour forexample, as shown in FIG. 6. In FIG. 6 the icon or indicia which is atick is shown in phantom outline for explanatory purposes.

To cause the icon or indicia to appear, a user's finger or thumb iswiped across the sign in the same way as previously described, from awipe-start region 2a if provided, as shown in FIG. 6. This will separateor release the upper sheet 3 from the base layer 2 as the user's fingermoves, so that the icon or indicia will again become visible, as shownin FIG. 7.

FIGS. 10 to 13 show yet another preferred form of sign of the invention.In this form an icon or indicia is printed as preferably a negativeimage 6 (or alternatively a positive image) on the upper sheet 3,preferably on the under side of the upper sheet 3. An icon or indicia isshown in the drawings as a tick printed on the under side of the uppersheet 3 as a negative image--see FIGS. 12 and 13. To cause the icon orindicia to appear, the upper sheet 3 is pressed against the backingsheet, for example, by pressing and repeatedly running a fingernail orsuitable stylus over the upper sheet. This will cause the upper sheet 3to adhere to the base layer 2 so that the colour of the base layer willappear through the upper sheet 3 where it is not printed with the layer6, to form the icon or indicia, as shown in FIG. 11. To cause the iconor indicia to become substantially less visible or generally invisible,a user's finger or thumb is wiped across the sign in the same way aspreviously described, from a wipe-start region 2a if provided, as shownin FIG. 11. This will separate the upper sheet 3 and the base layer 2 asthe user's finger moves, so that the icon or indicia will becomeinvisible or less visible, as shown in FIG. 10. Also as mentionedpreviously, a pattern which will tend to obscure the icon image i.e. thecolour of the base layer through the upper sheet 3 when the icon hasbeen erased, may be printed on to the upper sheet 3, for example on tothe top surface, such as a pattern of dots or wavy lines or similar.

FIGS. 14 to 18 show a further sign of the invention. In this form thebase layer 2 is either itself formed in the shape of an icon or indicia(a positive image as shown or alternatively a negative image) such asthe word APPLE, or the icon or indicia such as the word APPLE is printedin a contrasting colour below a layer of clear or near clear wax orsimilar coated over the printed icon or indicia, as in the sign of FIGS.1 to 5. An upper sheet icon or indicia, which in this case is an appleshape in-negative image, is printed on the top sheet, which is shown inthe drawings printed on the underside of the upper sheet at 6 (see FIG.18). The upper sheet icon or indicia could alternatively be a positiveimage.

In use when the upper sheet 3 is pressed against the backing sheet 1 theupper sheet will adhere to the base layer 2 so that the icon or indiciaof the base layer, which in this case is the word APPLE, becomes visiblethrough the window in the upper sheet 3 as shown in FIG. 15, the windowin this case being in the shape of an apple. The sign of FIGS. 14 to 18is essentially same as that of FIGS. 1 to 5 with the addition of awindow in the upper sheet which is preferably a negative image windowinterrelated to the base layer icon or indicia.

To change the sign so that the base layer icon or indicia issubstantially less visible or generally invisible, a users finger orthumb is wiped across the top surface of the label, from a wipe-startregion 2a if provided. This will separate the upper layer 3 and the baselayer 2 as the user's finger moves, so that the icon or indicia of thebase layer i.e. the word APPLE in this case, is no longer visible or isless visible through the window in the upper sheet, but the window inthe shape of the apple (or any other icon or indicia) will still bevisible as shown in FIG. 14.

In the sign of FIGS. 14, 15 and 17 the negative image printed on theupper sheet 3 is printed with an opaque or relatively opaque ink so thatthe upper sheet outside of the apple shaped window is opaque.Alternatively as shown in FIG. 16, the negative image on the upper sheetmay be printed with a translucent ink, or with a thin layer of aconventional ink so as to give the quality of translucence or in acolour that will match the apparent colour of the base material whenseen through the top layer adhered to the base layer. When the uppersheet is not adhered to the base layer the sign will appear similar toas in FIG. 14 (although the surrounding area of the upper sheet may notbe quite as prominent). When the upper sheet is "blocked in" with ablunt stylus or similar to cause it to adhere to the base layer so thatthe base layer icon or indicia becomes visible, the colour of the baselayer will show through the translucent top sheet surrounding thewindow, or alternatively a colour which is a combination of the baselayer colour and the upper sheet colour will be apparent surrounding thewindow. The edges of the window itself will not be clearly visible, asshown in FIG. 16.

In yet a further form of the sign of FIGS. 14 to 18 referred topreviously the coloured base layer is continuous (other than in awipe-start region) and a coating is applied over the top of the baselayer except in a region defining the shape of the base layer icon orindicia i.e. the coating is applied as a negative image of the icon ontop of the base layer (but the coating could also be applied as apositive image) When the upper sheet is pressed down by running anobject over the upper sheet the upper sheet will adhere to the baselayer where the coating is not applied but will not adhere to thecoating so that the icon or indicia will be visible through the uppersheet. To erase the icon or base layer indicia so that it is no longervisible a user's finger or thumb is wiped across the top surface of theupper sheet as before.

Again, to assist in making the base layer icon or indicia less visiblewhen the upper sheet is not adhered to the base layer, the colour of thebase layer icon or indicia may be made only medium contrast rather thanhigh contrast, and also the top side or under side of the upper sheetmay have printed onto it a pattern of small dots or wavy lines orsimilar which will tend to hide any shadowy image of the base layer iconor indicia that may still be visible through the upper sheet. Such apattern of dots or wavy lines or similar should not be sufficientlydense or large to obscure the icon when the upper sheet is pressed toadhere to the base layer to make the icon visible.

Instead of being printed as a window on the upper sheet the upper sheeticon or indicia may be printed as for example a positive image to oneside or above or below the area of the upper sheet where the base layericon or indicia is visible when the upper sheet is blocked in onto thebase layer. For example, the upper sheet icon or indicia may comprise apositive image of an apple which is printed to one side of where theword APPLE of the base layer is visible in one state of the sign. Whenthe sign is finger-wiped so that the upper sheet is separated from thebase layer the base layer APPLE word becomes not visible, but the appleimage on the top sheet is visible. The icon or indicia on the top sheetmay be printed so as to be always visible or so as to become invisibleor less visible when the state of the icon is changed, by merging intothe colour of the surrounding base layer colour.

FIGS. 19 & 20 show a further sign of the invention which comprises asmall sliding cursor between the upper sheet 3 and base layer 2 of thesign, which cursor is operated to separate or release the upper sheet 3from the base layer, instead of the previously described finger wipeaction. As before, the sign comprises an upper sheet 3 and a base layer2 on a backing sheet 1. The particular version shows in FIGS. 19 and 20is similar to the sign of FIGS. 1 to 4 in that a base layer icon orindicia is visible when the upper sheet 3 is caused to adhere to thebase layer 2, and is made substantially less visible or generallyinvisible when the upper sheet 3 is released from the base layer 2, bysliding of the cursor between the two as will be described. To form thebase layer 2 in this embodiment an icon or indicia which in this case isthe series of letters A, B, C, D is ink printed on the backing sheet asindicated at 2d and the base layer 2 comprises a coating of clear ornear clear wax or similar over the whole of the backing sheet. The uppersheet 3 extends over the base layer 2 as shown. A small frame 8, formedof plastic for example, is provided to the sign as shown and is fixedabout the periphery of the backing sheet 1. The sign is visible througha large window in the frame 8 as shown. A small plastic cursor 7 extendsacross the sign between the upper sheet 3 and base layer 2 as shown. Atits either end the cursor is captured within a slot extendingsubstantially the length of the frame 8 on either side.

To cause the base layer icon or indicia to be displayed, the upper sheet3 is pressed to adhere to the base layer 2 so that the base layer iconor indicia becomes visible through the upper sheet 3, by repeatedlyrunning a finger nail or stylus or similar over the upper sheet 3 withinthe window in the frame 8. To subsequently erase the icon or indicia orcause it to become less visible, the cursor 7 is slid in the directionof arrows I from one end of the sign to the other and back. As thecursor moves between the upper sheet 3 and the base layer 2 it willseparate same.

The particular version of signs shown in FIGS. 19 and 20 is similar tothat of FIGS. 1 to 5 except that the sign of FIGS. 19 and 20 uses cursorerasure instead of finger wipe erasure. It will be appreciated that asliding cursor instead of a finger wipe action could be used in any signof the invention including those if FIGS. 6 to 9, 10 to 13, and 14 to18. Also, other erasure systems may be utilised, such as joining theupper sheet to the base layer or backing sheet along one edge only sothat the upper sheet can be physically lifted to erase the sign.

Signs of the invention are preferably formed as a sealed unit therebypreventing the ingress of contaminates and improving mechanicalrobustness and structural integrity of the label. However, small airvents may be provided in the form of one or more slits or pinholes nearthe periphery of product such as at or near either end for example,which can assist in easy finger wipe action of the product, and also asmentioned the upper sheet does not necessarily need to be fixed to thebase layer about the entire periphery of the base layer so long as it isfixed along at least most of two opposite sides. The wiping actionemployed in use assists in redistributing the wax or other material ofthe base layer into any cavities formed by localised pressure duringwriting thus extending the life of the erasable product.

Preferably in manufacture of products of the invention, the upper sheet3 is applied to the base layer with little tension or minimal tension inthe material forming the upper sheet (but without excess slack in theupper sheet). For example, while the upper sheet may be subjected toslight tension in the manufacturing process which will take up some ofany inherent elasticity in the material of the upper sheet, it isundesirable for the material to be put under such tension as will takeup most of the inherent elastic extension that may be available with thematerial. Also, it is desirable that the upper sheet be laid onto thebase layer without excess air between the base layer and the uppersheet, but at the same time air does not need to be evacuated frombetween the upper sheet and the base layer.

The foregoing describes the signs of the invention and preferred formsthereof. Alterations and modifications and combinations of features notspecifically described as will be obvious to those skilled in the artare intended to be incorporated within the scope hereof as defined inthe accompanying claims.

We claim:
 1. A sign comprising a substantially clear base layer, acontrasting icon or indicia on a surface below the base layer, and anupper sheet extending over the base layer, the upper sheet and the baselayer being releasably adhered together under pressure applied on theupper sheet, and the icon or indicia being visible through the uppersheet when the upper sheet is caused to releasably adhere to the baselayer and being substantially less visible when the upper sheet isreleased from the base layer.
 2. A sign according to claim 1, whereinthe upper sheet and base layer are sufficiently releasably adheredtogether such that the upper sheet can be caused to release from thebase layer so that the icon or indicia can be made substantially lessvisible when a users finger or thumb is wiped across a top surface ofthe upper sheet to release the upper sheet from the base layer.
 3. Asign according to claim 2, wherein the upper sheet also extends over awipe-start region adjacent the base layer in which said region the uppersheet and the base layer are not adhered together, and over which saidregion a users finger or thumb may be placed to begin wiping movement toseparate the upper sheet from the base layer.
 4. A sign according toclaim 3, wherein material comprising the base layer is not providedbeneath the upper sheet in said wipe-start region to form the wipe-startregion in which the upper sheet and base layer are not adhesivetogether.
 5. A sign according to claim 2, wherein the upper sheetcomprises a transparent or translucent material.
 6. A sign according toclaim 2, wherein the upper sheet is fixed to a surface carrying the baselayer about all peripheral sides of the upper sheet and the upper sheetprovides a smooth and substantially wrinkle free top surface.